Telephone call and method therefor



Jan. 1925- 1,523,957

R. E. HALL TELEPHONE CALL AND METHOD THEREFOR Original Filed Aug. 13, 1919 x... WIRELESS TELEPHONE RECEIVINu SYSTEM L Wmnss TELEPHONE RECEIVING SYSTEM INVENTOR Patented Jan. 20, 1925.

UNITED STATES 1,523,957 PATENT OFFICE.

RAY EDWIN HALL, OF CHICAGO, ILLINOIS, ASSIGNOR TO HALL RESEARCH CORPORA- 'IION', A CORPORATION OF DELA'WARE.

TELEPHONE CALL AND METHOD THEREFOR.

Application filed August 13, 1919, Seria1 No. 317,117, Renewed. Ju1y 16', 1924.

To all whom it may concern Be it known that I, RAY E. I'IALL, a citizen of the United States, and resident of Chicago, in the county of Cook and State of 5 Illinois, have invented certain new and useful Improvements in Telephone Calls and Methods Therefor, of which the following is a specification.

My present invention relates to telephone calls particularly adapted for calling a wireless telephone receiving station. While particularly designed and peculiarly adapted for use in such a system, it possesses advantages which adapt it for other uses.

The practical art of telephoning by wireless, that is by electro-magnetic waves radiated from a sending station and received at a distant station has become a great practical success so far as concerns the transmission of speech, but so far as I am aware, no reliable calling system has been developed whereby the receiving operator may be summoned to the telephone. This is partly because the receiving amplifiers best adapted for reproducing articulate speech are not adapted for handling the relatively large amounts of energy necessary to operate a relay to close the circuit of an electric bell or buzzer adapted to be heard from a distance so and the primary object of my present invention has been to devise a simple auxiliary apparatus capable of giving such a call, without in any manner interfering with the functioning of the speech translating apparatus.

According to my present invention, I employ for this purpose a special form of relay which is very closely and selectively tuned to a single musical note. When it is desired to operate the call, this particular note may be sent out through the telephone transmitting apparatus of the sending station. It may be generated at that station either by sounding a. tuning fork or other musical l5 vibrator in the transmitting instrtunent to be transmitted and received in the same Way and by the same instrumentalities used to transmit the speech vibrations. Or, if desired, an ordinary interrupter of the required frequency may be used in the sending station. a

I have discovered, however, that unless special provision is made, a relay adapted to respond to a given note, is likely to be unintentionally and undesirably operated by musical vibrations or even ordinary vibrations of the voice in talking. With the particular form of tuned responsive device employed by me, this difficulty may be avoided by selecting as the calling note a frequency which does not occur either as a fundamental or as an important overtone in human speech. Indeed, the peculiar nature of my jet permits the use of call tones higher than any speech :t'requencies, and, so far as concerns the principle of the device, the frequency may be nearer or even above the limit of audibility.

While the above expedient may be useful in many cases, it is obvious that it involves greatly limiting the number of notes that can be used and this tends to limit the number of receiving stations that may be tuned so as to respond to a single calling station selectively and to the exclusion of other receiving stations of the same telephone system. Hence, another important feature of my invention consists in providing a very sluggish relay which will not respond unless the calling note is greatly prolonged as well as being of the correct frequency. With such arrangement the call will not be operated by speech waves, which, even .if of the correct frequency, will not last long enough to operate the relay.

The particular form of relay which I employ is a sensitive jet, preferably of air, discharged through a suitable nozzle and under considerable pressure in combination with a telephone receiver and resonator associated with a telephone receiving system and adapted to break down the jet by applying to the sensitive base thereof the acoustic air waves of the calling note propagated from the telephone diaphragm. The jet discharges in operative relation to a sensitive resistance wire or filament in series with a local battery circuit. The sensitive resistance is preferably heated to a high temperature by the battery current flowing therethrough and the jet is arranged so that it normally discharges near to but not upon the said resistance so as to have but little cooling effect thereon. When the j et is broken down, however, it bushes or spreads and chills the wire. Thebreaks of the jet correspond to the frequency of the calling note and the successive breaks operate to lower the average temperature of the wire and thereby permit greatly increased flow of battery current therewaves by the telephone receiver.

through? In the local battery circuit is an electro-magnetic relay adjusted so that 'its switch will not be closed by the normal currentfiowing through the hot wire but will be closed by the greater cur-rent which flows when said wire is cooled and its reslstance thereby lowered. Closing the relay switch may be utilized to operate an ordinary buzzer, call bell, whistle or klaXon according as the receiving operator is likely to be near to-or remote from the telephone receiving station. The desiredsluggishness of response may be promoted by employment of a special foirhn of resonator which delays the time'of building-up a resonant note-suflicient to=break down the jet, and by using a relatively heavy wire affording considerable mass to be heated and a correspondingly decreased cooling surface area.

The specialtorm of resonator is preferably'employed'in novel combination with a jet constitutedand'adjusted'so as to be insensitive in the direction of air waves proceeding from-the receivingtelephone but sensitivetowaves proceeding-at right angles thereto.- I

Figurel is a diagrammatic view of a simple'form of my invention;

Figure 2 is a diagram of a modification; and

Figure 3 isf-a horizontal section through the special-form of resonator shown in Figure 2/ V In the drawingsthe:receiving station is diagrammatically indicated'as comprising a i'eceivingconductor A adapted to receive and be energizedby the radiant electro-magnetic waves from the sending station; This energy is conveyed to and t'ranslatedintoelectrical-undulations corresponding to speech by suitable translating apparatus dlagrammaticallyqindic'ated at-B. These electrical 'nndulationis are-translated into speech air These parts of the telephone system 1 may be of any 1 known or desired construction. The call which I employ in connection-with said construction consists of a telephonereceiver Dadapted tobe cut into or out of circuit of receiver C, by means of switch E. Receiver C may be cut in or out by means of switch F.

As shown inFigure 1, the receiver D has a tubular re'sonator 1, secured over the face In this connection l utilize at least two aircolumn resonators, one func-' attracting the tapper.

thereof in operative relation to the receiving diaphragm so that the air column of the res onator will be set in vibration by the vibrations of said receiver diaphragm. The air column of resonator 1 is tuned to the frequency of the note selected as the call note of the receiving station. The diaphragm of: the receiver may be tuned to the same frequency and the coil of the receiver magnet operating the diaphragm may be proportioned and wound for best operation when energized by waves of said frequency.

The resonator 1 preferably has a contracted orifice 2 located in close proximity to the side of the discharge orificefl of nozzle 4. Nozzle 4. is supplied with air under a suitable, preferably adjustable pressure supplied by means not shown. The nozzle is formed anduidjustcd so that normally the jet issuingthercfrom is a smooth columnof approximately uniform diameter but in a condition where increased pressure would cause it to bush or break. Normally the smooth jet discharges in close proximity to the sensitive resistance wire or filament 5 without impingement thereon. The sensitive resistance 5 is preferably 1n the form of a hollow coil arranged so that the smooth jet normally discharges through the axis thereof. hen the jet is broken down and bushes, however, it impinges on the wire and cools it thus lowering its resistance. The sensitive resistance 5 is in series with battery 6 and the winding 7 of magnet 8 controlling relay switch 9. The amount of such nor mal current is controlled by sensitive resistance 5 which is of proper size andlength to be heated to a high temperature and to opposea high resistance to the flow of battery current: When the jet breaks and impinges on the sensitive resistance, it cools it and greatly'lowers its resistance thus permitting greatly increased flow of battery current. The relay is adjusted so that its switch will not be closed by the normal current flowing in the battery circuit when the resistance 5 is hot but will bcclosed by the greater current'fiowingt in'said circuit when the resistance is cool.

The relay switch controls the indicator circuit, the indicator in this case being diagrammatically represented as an ordinary 'elcctroanugnct call hell (i. This may'operate in the usual way by battery 10 energizing electro-magnct ll there by attracting the vibratory bell tapper 12 thereby breaking the circuit at 13 thus de-energizing magnet 11 and releasing the tapper which is retracted by spring 1451, thereby again closing circuit at 13 and again Thus the bell continues ringing as long as relay switch remains closed which is as long as the resist ance 5 remains cool which is as long as the breaking of the-jet continues which is'as liltl long as the call note sounds in telephone D which is as long as the call note is received from the sending station or until the operator responds and opens switch E.

If desired for special purposes, the call may be made still more exclusively selective by adding one or more relay switches in the call bell circuit so that the circuit Will not be closed unless both relays are operated si multaneously.

Such additional relay will be in a separate battery circuit, controlled by another hot wire, cooled by another jet, broken down by another telephone receiver, energized either in series or parallel with the above described receiver D. In such case the additional apparatus will be tuned a different frequency so that it will require two calling notes, simultaneously sounded in the talking circuit, in order to close both relays and sound the call bell.

My calling system and methods herein disclosed are applicable to wireless telegraph systems. In such case the wireless telegraph receiving system may be substantially identical with the telephone system herein disclosed. The sending system, how ever, will have to be provided, or capable of being provided with means whereby the radiated waves will have the characteristics of a note. In case of spark telegraphy, the spark frequency will be the note to which my jet relay will be tuned. In the system operating by the continuous radiation method, an interrupter of the desired frequency can be employed at the sending station.

Various specific forms of jet relay apparatus and methods of ope 'a-ting the same, suit able for the practice of my present invention are more fully disclosed in my Patent No. 1,378,345 to which reference is hereby made. i

In the above described arrangement shown in Figure 1, the desired sluggishness of response to prevent accidental operation of the call by voice frequencies depends upon the proportions and characteristics of the sensitive resistance If this resistance is made of platinum wire of considerable diameter, the mass of metal heated will be great as compared with its cooling surface, consequently it will not. cool quickly and it will not change its resistance sufficiently to operate the relay switch until the breaking of the jet has been continued for a desired length of time. As a sluggish, sensitive resistance, suitable for this purpose, I have used platinum wire of .001 to' .005 inch in diameter. The sluggishness may also be increased to a certain extent by adjusting the jet to a more moderate, less sensitive pressure so that it will be operated only'by a note louder than ordinarily used in speech. The utility of'this expedient is limited, however, because the efficiency of wireless transmission is extremely variable and in general it is more desirable to have the call operable by even the faintest call note in telephone D. I therefore prefer that the desired sluggishness of the jet should be attained by special means which, while giving the desired slow or delayed response, Will do so by means not involving any decrease of sensitiveness. Means whereby this result may be obtained are indicated in Fig-- ure 2.

Figure 2 has all of the above mentioned parts described in connection with Figure 1, the only difference being in the form of the nozzle and sensitive jet discharge therefrom and also in the substitution of a system of air column resonators in place of the simpleresonator 1 of Figure 1.

In Figure 2 the jet nozzle is quite like that of Figure 1 but is flattenecha desirable proportion for the jet orifice being say one eighth inch long by one-sixt-y-fourth inch wide, the sides being parallel.- Such a jet is very insensitive to air waves acting edgewise thereon. I therefore arrange the projector tube 21 of receiver D edgewise to the jet so that it will not act thereon directly and I provide a secondary resonator 22 at right angles to 21 and directed fiat-wise toward the base of the jet. The air waves in 21 are utilized to excite resonant vibration in resonator 22 which is a stopped tube of proper length to afford air column resonance in response to the call note of the receiving station. The building up of reso nance in 22 is facilitated by the use of another resonator 23 in axial alignment with 21 with its open mouth directed toward the other insensitive edge of the jet. 2?) is and 21 may be tuned'to the same frequency as 22. When the call note sounds in 21, resonant vibration is gradually built up and the resonator 23 thereby'excited to sympathetic resonance. The vibration of air column 22 being directed against the flat sensitive side of the jet breaks it down. These successive buildings up of resonance require a. more or less prolonged excitation and the frequency of the call note occurring accidentally in speech will not continue long enough to build up the resonance and operate the call although singing a prolonged note of correct pitch would do so.

By varying the length of pipes'21, 22, 23, various effects analogous to the above may be produced, the building up of sympathetic resonance of 22, to harmonic frequencies or beat frequencies being even slower than where the resonators are all tuned to the same frequency-the frequency of the calling note.

It will be understood by those skilled in the art that certain features of my invention may be employed in connection with otherv arrangements of sensitive jet and other devices responsive to changes of the jet, as for instance those disclosed in my prior Patents Nos. 1,160,072 and 1,205,530. Also,-- the sensitive resistance may be arranged so as to be normally cooled by the jet and to heat up when the breaks, or the relay controlled by the jet may be normally closed and arranged to openwhen the jet breaks. In certain cases, also, sensitive flames may be employed to normally heat the sensitive resistance, in such case the change of resistance being due to withdrawal ofthe flame when the jet breaks.

The unignited'cooling jet, however, isfa-r preferable inevery way. Air is the most convenient cooling fluid to use but other gases may be employed if desired and they may be artificially refrigerated, though this is not necessary. The wire may be of material other than platinum. It may be of iron and may be proportioned so as to be normally heated by the battery current-1 up to" the critical high temperature where its changeof resistance is much more than: proportion'al to its change of temperature, and, where iron is used, the jet maybe of hyd ro gen, nitrogen, carbon dioxide or even illuminating gas.

' I claim:

1. In the art of Wireless telephony, the method of calling a receiving station equipped with the usual apparatus for wireless telephonic receiving and also with means for producing a call observable at a distance, which method consists in emit-ting from the calling station electrical waves representing a note of definite frequency, utilizing the energy of said waves by wire" less telephonic methods to reproduce said note at the receiving station as acoustic waves propagatedin a gaseous medium, establishing a gaseous et andmaintaining it in a condition sensitive to acoustic waves of said frequency, applying the energy of said acoustic waves to said jet, and utilizing the resultingbreaking or bushing of the jet to control operation of the calling device.

2; In the art of wireless telephony, the method of calling a receiving station equipped with the usual apparatus for wireless telephonic receiving and also with means for producing a call observable at a distance, which method consists in emitting from the calling station electrical waves representing a note of definite frequency, utilizing the energy of said waves by wire less telephonic methods to reproduce said note at the receiving station as acoustic waves propagated in a gaseous medium, establishing a gaseous jet and maintaining it in a condition sensitive to acoustic waves of said frequency, applying the energy of said acoustic waves to said jet and utilizing the resulting breaking or: bushing of the jet to change the temperature of a heat sensitive device, utilizing the resulting change in a condition or quality of the latter to control currentflow in a local circuit, and utilizing such changed current flow to operaite the call;

3. In the art of wireless telephony, the method of calling a receiving station equipped" with the usual aparatus for wireless telephonic receiving and also with means forproducing a call obser *able at a distance, which method consists in emitting from the calling station electrical waves representing a note of definite frequency, utilizing the energy of said waves by wireless telephonic methods to reproduce said note at the receivingst'ation as acoustic waves propagated in a gaseous medium, establishing a gaseous jet and maintaining it in a condition sensitive to acoustic waves of said frequency, applying the energy of said acoustic waves to said jet, and utilizing the resulting breaking or bushing of the jet to progressively cool a heat-sensitive resistance normally heated by How of electric current therein, utilizing the resulting change in a condition or quality of the latter to control current flow in a local circuit, and utilizing such changed current flow to operate the call.

4'. In the art of wireless telephony, the method of calling a receiving station equipped with the usual apparatus for wireless telephonic receiving and also with means for producing a call obsciyable at a distance, which method consists in emitting from the calling station electrical aves representing a note of definite frequency. utilizing the energy of said waves by wireless telephonic methods to reproduce said note at the receiving station as acoustic waves propagated in a gaseous medium, establishing a gaseous jet and maintaining it in a condition sensitive to acoustic waves of said frequency. applying the energy of said acoustic *avcs to said jet, and utilizing the resulting breakin or bushing of the jet to cumulatively a cot a relay device selectively responsive to said frequency but having a time period of response which is long as compared with the duration of: any frequency of human speech, and utilizing the cinnulative effect of said air waves on said relay device to control. the circuit of the calling device.

5. Apparatus for increasing the selectivity and increasing the time period of response of a. sensitive jet adapted to break or bush in response to air waves of a definite frequency, including means for applying the primary air waves indirectly to excite sympathetic rcasonance of an air column resonator having a natural frequency responsive to that of said waves and arranged to apply to the base of the jet the amplified air oscillations resulting at the ventral end of said air-column.

6. Apparatus for increasing the selectivity and increasing the time period of response of a sensitive jet adapted to break or bush in response to air waves of a deiinite frequency, including means for applying the primary air waves indirectly to excite sympathetic resonance of an air column resonator having a natural frequency responsive to that of said waves, and in operative relation to the amplified air oscillations occurring at the open end of said resonator a second resonator adapted to be excited to sympathetic resonance, arranged to apply to the base of the jet the amplified air oscillations resulting at the ventral end of said air column.

7 A wireless telephone receiving system including a conductor for receiving telephonicly varied electro-inagnetic waves, translating devices for utilizing the received energy to reproduce the telephonic variations as sound waves in the air, and, in combination therewith, a cooling jet tuned so as to be selectively sensitive to air waves of a predetermined frequency, means for applying to said jet air waves reproduced by the translating devices, circuit controlling means operated by breaking or bushing of said jet when said reproduced air Waves are of said predetermined frequency, a local circuit controlled thereby and a call operated through changes of current in said local circuit.

8. A wireless telephone receiving system including a conductor for receiving telephonicly varied electro-magnetic waves, translating devices for utilizing the received energy to reproduce the telephonic variations as sound waves in the air, and, in combination therewith, a cooling jet tuned so as to be selectively sensitive to air waves of a predetermined frequency, an air column resonator having an open end thereof adjacent the sensitive base of said jet, means for applying air waves reproduced by the translating devices to cause sympathetic resonant oscillation of said resonator, circuit controlling means operated by breaking or bushing of said jet when said reproduced air waves are of said predetermined frequency, a local circuit controlled thereby and a call operated through changes of current in said local circuit.

9. A Wireless telephone receiving system including a conductor for receiving telephonicly varied electro-magnetic waves, translating devices for utilizing the received energy to reproduce the telephonic variations as sound waves in the air, and, in combination therewith, a cooling jet tuned so as to be selectively sensitive to air waves of a predetermined frequency, means for applying to the sensitive base of said jet the energy of air waves reproduced by the translating devices, said means including an air column resonator tuned to said predetermined frequency, and excited to resonance by said air waves, circuit controlling means operated by breaking or bushing of said jet when said reproduced air waves are of the required frequency, a local circuit controlled thereby and a call operated through changes of current in said local circuit.

10. A wireless telephone receiving system including a conductor. for receiving telephonicly varied electro-magnetic waves, translating devices for utilizing the received energy to reproduce the telephonic variations as sound waves in the air, and, in combination therewith, a cooling jet tuned So as to be selectively sensitive to air waves of a predetermined frequency, means for applying to the sensitive base of said jet the energy of air waves reproduced by the translating devices, said means including a plurality of air column resonators adapt ed to be successively excited to sympathetic resonance by prolonged action of the air waves, circuit controlling means operated by breaking or bushing of said jet when said reproduced air waves are of the required frequency, a local circuit controlled thereby and a call operated through changes of current in said local circuit.

Signed at Montreal, in the Province of Quebec and Dominion of Canada this 8 day of August, A. D. 1919.

RAY EDXVIN HALL. 

